Gas turbine with variable blade distributor

ABSTRACT

An annular guide ring between a high pressure turbine rotor and a low pressure turbine rotor is provided with pivotal blades operable by a common ring gear and biased radially inwardly against an inner annular casing by a spring surrounding the pivot shaft of each blade.

United States Patent Dekeyser [4 1 Aug. 22, 1972 1541 GAS TURBINEWITH VARIABLE 3,574,479 4/1971 Barnard ..415/160 BLADE DISTRIBUTOR Y [72] lnventor: Lucien Dekeyser, 23 Avenue de la FOREIGN PATEN'IS OR APPLICATIONS Rochelle, Chelles, France [73] Assigneez Bennes Martel, Saint Etienne 755,527 8/1956 Great Britain ..415/161 (Loire) France 878,988 10/1961 GreatBritain...' ..415/162 [22] Filed: Aug. 5, 1970 [21] A l. N 61,205 Primary Examiner-Henry F. Raduazo Attorney-Sughrm, Rothwell, .Mion, Zrnn & 'Macpeak Foreign Application Priority Data A Aug. 14,1969 France ..6928154 7 ABS v I An annular guide ring between a high pressure turbine [52] US. Cl. ..'.....415/159, 415/160, /39.17 r tor and a lo pressure turbine rotor is pr vided with [51] Int. Cl. ..F01d 17/00, F02c l/06 piv al blades operable by a common ring gear and [58] Field of Search ..415/ 160, 161, 162, 159, 147; biased radially inwardly against an inner annular cas- 6()/39 17 ing by a spring surrounding the pivot shaft of each blade. I [56] References Cited 1 Claims Drawing Fi UNITED STATES PATENTS 3,013,771 12/1961 Henny ..415/

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SHEET 2 [IF 4 GAS TURBINE WITH VARIABLE BLADE DISTRIBUTOR This invention relates to a gas turbine.

It is known to produce a gas turbine comprising, on the one hand, a primary shaft on which are keyed the rotor of a centrifugal compressor and the rotor of a high pressure turbine, and, on the other hand, a secondary shaft or power shaft on which are keyed one or more low pressure turbine rotors. Between the high pressure rotor and the low pressure rotor(s) there is located a guide ring provided with fixed blades. This known structure is described, for example, in French Patent Application No. PV Rhone 30,194, filed on July 8th 1968 in the name of the present applicant.

This system is satisfactory for gas turbines rotating under practically constant working conditions and load. However, disadvantages result if it is proposed to use a turbine of this type at different speeds and loads, for example, if it is desired to equip a lorry or any other motor vehicle with it. It is thus desirable, on the one hand, to improve the efficiency for partial loads, and, on the other hand, to reduce the starting time of the turbine, and finally to ensure the effect of a turbine brake on the vehicle.

The object of the present invention is to achieve these results by producing an improved gas turbine specially adapted for driving a lorry or a motor vehicle.

According to the present invention there is provided a gas turbine comprising an annular guide ring located between a high pressure turbine rotor of a primary shaft and a low pressure turbine rotor of secondary shaft, the guide ring having pivotal blades arranged radially around the central axis of the turbine, each blade being mounted on a shaft provided with a pinion meshing with a gear ring coaxial to the general axis of the turbine, rotation of the gear ring being controlled by driving means.

These driving means preferably comprises a doubleacting jack which is connected by a connecting-rod to a bracket on the gear ring. This jack may advantageously be constituted by a piston movable in a cylinder, in one direction, under the thrust of a compressed fluid and in the opposite direction, under the action of a spring, the pressure of the fluid for controlling the jack being variable by a regulator. This regulator can be controlled either manually, or automatically, or by a combination of both.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a sectional view on the line I I of FIG. 2 of a gas turbine according to the invention;

FIG. 2 is a section on the line H II of FIG. 1;

FIGS. 3 and 4 are detail views of parts of FIG. 2;

FIG. 5 is a diagrammatic section on the line V V of FIG. 2; FIG. 6 is a developed view showing the orientation of the movable blades of the guide ring during the starting phase of the turbine;

FIG. 7 is a similar view to FIG. 6 corresponding to conditions of maximum power; and,

FIG. 8 illustrates the operation as an engine brake.

There is shown in the drawings a guide ring according to the invention which is fitted to a gas turbine whose general structure is similar to that disclosed in French Application No. 69,155,49 filed on May 22nd 1969 in the name of the present applicants.

This turbine comprises a centrifugal compressor 1 and a high pressure bladed rotor 2 keyed on the same shaft 3, and a low pressure bladed rotor 4 which constitutes the power wheel which drives the output driving shaft 5 through the intermediary of a reduction gear 6. At the front of the turbine, the shaft 3 drives the elements of a gear box 7. The admission of atmospheric air takes place through lateral intakes 8 while the exhaust gases are returned to atmosphere through two inlets 9 directed towards the rear of the turbine.

Two rotating heat exchangers 10 are inserted respectively:

in the air admission circuit (arrows 11), the air being driven by the compressor 1 towards the combustion chambers 12;

in the path of exhaust gases (arrows 13) which are directed by the rotor 4 in the direction of the exhaust outlets 9.

Between the high pressure turbine rotor 2 and the low pressure turbine rotor 4, there is inserted a guide ring which constitutes the present invention.

This guide ring comprises, immediately behind the high pressure rotor 2, arms 14 which support an internal annular element 55 for ensuring the continuity of the air jet. Behind these arms 14, is provided a group of movable blades 16. Thus, gases leaving the high pressure rotor 2 pass between the arms 14, then traverse the blades 16 before driving the power rotor 4.

The blades 16 are distributed radially about the general axis of the turbine. They are all identical and equidistant. For example, there may be eighteen blades 16, although it is to be understood that this number is given purely as an example.

At is outer radial end, each blade 16 is integral with a journal 17 surmounted by a shaft 18. On the free end of this shaft 18 there is keyed a toothed pinion 19.

The base 20 and the top 21 of each blade 16 are machined to a spherical profile in order to ensure, either contact, or minimum play, with the stationary parts which surround them, namely an internal, annular casing 22 and an external, annular casing 23. Thus, airtightness is ensured, whatever the angular position of the blades 16 and their journals 17.

Each journal 17 rotates in a fixed, bearing 24, and a ring 25 constitutes another bearing in which each shaft 18 rotates. The rings 24 and 25 are housed inside a fixed column 26.

At the junction of the journal 17 and the shaft 18 which is of smaller diameter, there is, at the level of a shoulder 27, supported a washer 28. The latter receives the thrust of a helicoidal compression spring, the opposite end of which is in abutment with a socket 25. The latter is immobilized in the axial direction by a circlip 30 provided on top of the column 26. Thus, the spring 18 housed between the two rings 24 and 25 ensures the contact of the base 20 of the blade !6 with the fixed spherical casing or part 22. This contact force is increased during the operation of the turbine, due to the effect of the air pressure acting on the end of the shaft 18 (FIG. 4, arrow 31), it being known that the annular enclosure 32 which surrounds the guide ring 14, 16 is in communication with the delivery air pressure of the compressor 1 (FIGS. 1 and 2).

This contact between surfaces 20, 22 at the base of each blade assists in retaining the blade in position and avoidance of vibrations.

The pinions 19 preferably have conical toothing and they all mesh with a toothed wheel rim 33 which surrounds the guide rings 16. The guidance of this toothed rim 33 is ensured by two ball-races or rollerraces. 34

and 35.

The rim 33 comprises a lateral bracket 36 FIG. on which there is pivoted by a shaft 37 one of the ends of a coupling rod 38. At its opposite end, this rod is connected by a pivot 39 to the piston rod 40 of a jack. This jack comprises a piston 41 integral with the rod 40, which piston slides inside a fixed cylinder 42. Between the end wall 43 of the cylinder 42 and the piston 41, there is housed a compression spring 44. On the other side of the piston, i.e. near the other end wall 45, there is defined a variable volume chamber 46 which receives by known means which are not shown,- the oil of the hydraulic circuit for regulating the'turbine.

As regards the fixed arms 14, they have a transverse profile 47 as shown in FIG. 3, each arm being hollow, i.e. over their entire length there are channels 48 through which cooling air can circulate.

The operation of the guide ring is as follows:

As hydraulic pressure builds up in the chamber 46 of the jack 41, 42, or on the contrary, as the piston 41 is allowed to return under the thrust of the spring 44, it will be understood that the toothed rim 33 is cased to rotate in one direction or in the other (FIG. 5, double arrow 49). This rotary movement is transmitted simultaneously to all the pinions 19, such that all the blades 16 turn at the same time by the same angle.

When the blades 16 occupy the position illustrated in FIG. 6 they offer the maximum passage to the gases escaping from the generating rotors (arrow 50). Thus the explosion rate of the high pressure turbine 2 is increased. This position, corresponds to the starting conditions of the turbine, or even to its slow-running conditions.

When, due to rotation of the shafls 18, the blades 16 are brought into the position shown in FIG. 7 (arrows 51) the turbine is at maximum power conditions, the rotor 4 being itself at nominal speed.

When finally, due to rotation in the opposite direction (arrows 52), the blades 16 are brought into the position shown in FIG. 8, and the gases which come from the fixed guide-ring defined by the arms 14 flow in the direction of the arrow 50 and are deflected towards the rear and leave in'the direction of the arrows 53.v

Thus, they tend to oppose the rotation of the low pressure rotor 4 which moves in the direction of the arrow 54. Thus the turbine operates as an engine brake. Finally, it can be seen that the turbine according to the invention using a guide ring with pivotal blades 16, has the following advantages:

reduction of starting time of the turbine; reduction of the inlet temperature during the starting-up phase;

reduction of the temperature under slow-running conditions and, consequently, reduction of consumption under these conditions;

reduction of consumption with partial leads;

action as engine brake by inversion of the gas jet.

It is interesting to note that the first three of these advantages are similar to those which are obtained by the use of by-pass valves as disclosed in French Patent Apl' ti N P.V. 68% thg name sequently, it is no longer necessary to provide these bypass valves on a gas turbine having a guide ring with pivotal blades according to the present invention.

1 claim:

1. In a gas turbine of the type having a high pressure turbine rotor, a low pressure turbine rotor and an intermediate annular guide ring disposed coaxially in a casing wherein said guide ring includes a plurality of blades each of which is mounted for rotation about an individual radially extending axis by means of a common gear ring disposed in meshing engagement with a pinion coaxially secured to each blade with each blade bearing on an inner spherical surface of said casing, the improvement comprising a plurality of stepped shaft means each having a pinion and a blade secured to opposite ends thereof, a pair of spaced apart bearing rings supporting each of said shafts in said casing, means locating each outermost bearing ring against radially outward displacement and spring means disposed intermediate each of said outermost bearing rings and a stepped portion of each stepped shaft whereby each of said blades is biased radially inwardly against said spherical surface.

i lii l 

1. In a gas turbine of the type having a high pressure turbine rotor, a low pressure turbine rotor and an intermediate annular guide ring disposed coaxially in a casing wherein said guide ring includes a plurality of blades each of which is mounted for rotation about an individual radially extending axis by means of a common gear ring disposed in meshing engagement with a pinion coaxially secured to each blade with each blade bearing on an inner spherical surface of said casing, the improvement comprising a plurality of stepped shaft means each having a pinion and a blade secured to opposite ends thereof, a pair of spaced apart bearing rings supporting each of said shafts in said casing, means locating each outermost bearing ring against radially outward displacement and spring means disposed intermediate each of said outermost bearing rings And a stepped portion of each stepped shaft whereby each of said blades is biased radially inwardly against said spherical surface. 